Electro-erosion machining apparatus, such as EDM machines, are often provided with a wire electrode in the form of a metallic wire fed between a pair of support and guiding members. The electrode wire is fed longitudinally in a predetermined direction and has a given free or unsupported length stretched between the support and guiding members. The wire axis and the workpiece are displaced relative to each other so as to effectuate a machining or cutting operation in the workpiece by electroerosion, while maintaining a predetermined machining gap between the wire and the workpiece surface in the course of a cut. In conventional devies of this type, transverse oscillations of the wire may take place in the machining zone at the unsupported portion of the wire between the pair of support and guiding members. This is due to the fact that any elastic stretched wire has a particular resonant fundamental frequency, and several harmonics, the resonant fundamental frequency being inversely proportional to the length of the wire between supports. In any wire electrode EDM machine, the wire oscillations may be caused by mechanical vibrations of diverse origins such as due, for example, to the pulse characteristics of the machining current or to the non-continuous motion of the workpiece being incrementally fed relative to the wire electrode.
As soon as the wire electrode oscillates or vibrates transversely, the machining quality rapidly deteriorates, and the machined surface may even be slightly bulged instead of being straight. In addition, the wire electrode oscillations causes undesirable short circuits to occur between the wire and the workpiece, thus resulting in a considerable decrease of machining efficiency.